Hydrogen production reactions from carbon feedstocks: fossil fuels and biomass.

Density functional theory methods for characterization of porous materials

Recent progress in syntheses of porous carbons with designed pore architecture has rejuvenated the field of carbon chemistry and promises to provide new advanced materials. In order to reap the full benefit of designer carbons, it is necessary to develop chemistries for functionalizing the porous carbon surfaces. This Review examines methods of functionalizing porous carbon through direct incorporation of heteroatoms in the carbon synthesis, surface oxidation and activation, halogenation, sulfonation, grafting, attachment of nanoparticles and surface coating with polymers. Methods of characterizing the functionalized carbon materials and applications that benefit from functionalized nanoporous carbons with designed architecture are also highlighted.

Functionalization of Porous Carbon Materials with Designed Pore Architecture

Great progress has been made in the preparation and application of ordered mesoporous metal oxides during the past decade. However, the applications of these novel and interesting materials have not been reviewed comprehensively in the literature. In the current review we first describe different methods for the preparation of ordered mesoporous metal oxides; we then review their applications in energy conversion and storage, catalysis, sensing, adsorption and separation. The correlations between the textural properties of ordered mesoporous metal oxides and their specific performance are highlighted in different examples, including the rate of Li intercalation, sensing, and the magnetic properties. These results demonstrate that the mesoporosity has a direct impact on the properties and potential applications of such materials. Although the scope of the current review is limited to ordered mesoporous metal oxides, we believe that the information may be useful for those working in a number of fields.

Ordered mesoporous metal oxides: synthesis and applications.

Semiconducting metal oxides are frequently used as gas-sensing materials. Apart from large surface-to-volume ratios, well-defined and uniform pore structures are particularly desired for improved sensing performance. This article addresses the role of some key structural aspects in porous gas sensors, such as grain size and agglomeration, pore size or crack-free film morphology. New synthesis concepts, for example, the utilisation of rigid matrices for structure replication, allow to control these parameters independently, providing the opportunity to create self-diagnostic sensors with enhanced sensitivity and reproducible selectivity.

Porous Metal Oxides as Gas Sensors

Mesoporous CeO2 : Synthesis by nanocasting, characterisation and catalytic properties

Studies on the state of iron oxide nanoparticles in MCM-41 and MCM-48 silica materials

Cobalt-containing MCM-41 and SBA-15 mesoporous materials were prepared by the pH-adjusting of the impregnation solution. The modified materials were investigated by X-ray diffraction, N2 physisorption, temperature-programmed reduction, DR UV–Vis diffuse reflectance, and FT-IR spectroscopy of adsorbed pyridine. The pH of the impregnation solution influences the surface charge of the mesoporous support and therefore determines the strength of interaction between the cobalt precursor and the mesoporous support. The formation of different cobalt oxide species in different ratios, depending on the pH of the impregnation solution, was established for both materials. The modified Co/MCM-41 and Co/SBA-15 materials were active in toluene oxidation. Their catalytic activity is predetermined by the nature, the reducibility, and the dispersion of the obtained cobalt oxide species.

Catalytic activity of Co/MCM-41 and Co/SBA-15 materials in toluene oxidation

Adsorption of CO at 85 K on Cu/MCM-48 results in formation of Cu + (CO)2 species (2162 and 2121 cm −1 ) H-bonded CO (2156 cm −1 ) and a negligible amount of Cu 2+ –CO carbonyls. Decrease of the coverage is accompanied by decomposition of the OH–CO and Cu 2+ –CO species while the Cu + (CO)2 dicarbonyls loose one ligand and are converted into Cu + –CO species (2130 cm −1 ). The assignments are proved by co-adsorption of 12 CO and 13 CO. CO adsorption on the hydrogen-reduced sample provokes formation of Cu 0 –CO species characterized by a band at 2122 cm −1 . The latter are easily decomposed upon evacuation. Low temperature CO adsorption on Cu/MCM-41 leads to formation of the same species as observed with Cu/MCM-48. In this case, the concentration of the Cu + –CO species is higher and a significant amount of Cu 2+ –CO species is detected. These results suggest a higher dispersion of copper on MCM-41. The frequencies of the Cu + (CO)2 (2163 and 2127 cm −1 ) and Cu + –CO (2134 cm −1 ) species on Cu/MCM-41 are slightly blue shifted. The frequency of the Cu 0 –CO species (2125 cm −1 ) is also a little higher. In line with the higher copper dispersion, Cu/MCM-41 is superior to Cu/MCM-48 in its catalytic activity for the methanol decomposition to hydrogen and CO. The peculiarities of the samples depending on the preparation method are discussed. © 2002 Elsevier Science B.V. All rights reserved.

Christo Minchev

Papers

Mesoporous CeO2 : Synthesis by nanocasting, characterisation and catalytic properties

Studies on the state of iron oxide nanoparticles in MCM-41 and MCM-48 silica materials

Catalytic activity of Co/MCM-41 and Co/SBA-15 materials in toluene oxidation

Characterization of Cu/MCM-41 and Cu/MCM-48 mesoporous catalysts by FTIR spectroscopy of adsorbed CO

Cobalt-modified mesoporous MgO, ZrO2, and CeO2 oxides as catalysts for methanol decomposition.